This invention is concerned with covers for tanks or open channels. In particular, the invention relates to a modular cover for a tank or channel of elongated shape, but width in the range of about eight to twenty feet, especially useful in sewage treatment tanks wherein a seal may be required and wherein access openings are required in the cover.
Increasingly there is a need for covers to enclose in-ground and above ground tanks used for storing waste materials including sewage, chemical sludge, petroleum products and other volatile and odorous materials. The materials generally are stored for later disposal or treatment in such tanks. Such a cover must be substantially gas tight for controlling odors in the vicinity of the tank site and for trapping potentially hazardous gases.
A tank cover is generally too large to be conveniently or cost effectively shipped in an assembled form from a manufacturer to the site of the tank. Because of this, tank covers for relatively large tanks are generally shipped as components and assembled at the site.
Prior art tank covers made of steel are heavy and expensive even to ship in component form. Further, such covers usually require welded connections and bolted connections in their assembly. As such, skilled personnel may be necessary to carry out the assembly, and the assembly process may be lengthy and costly. Some prior tank covers have been formed of sheet metal panels assembled at the site.
Tank covers for specific purposes are disclosed in U.S. Pat. No. 5,325,646 and U.S. Pat. No. 5,617,677. The latter discloses, in one embodiment, a cover for an elongated and narrow tank or channel. That cover is made up of a series of panels connected end-to-end, with deck planks of the panels extending transversely; thus, each plank spans essentially across the entire channel, avoiding the need for structural spanning members (other than the deck planks themselves) to extend across the channel.
Although utilizing deck planks or slats similar to those in the above-referenced copending application, the present invention uses the planks in a different orientation, for elongated tanks or channels having a width generally in the range of about 8 to 20 feet, and with special structural cross members which provide for efficient prefabrication and transport of individual panels, minimal construction time at the site, and the ability easily to remove some of the panels when needed for access to the tank.
The disclosures of the above-referenced copending application and issued patents are incorporated herein by reference.